Polarizing plates have widely been used in displays such as liquid crystal displays, in particular recently in flat-panel televisions and various mobile devices. A polarizing plate obtained by bonding a protective film composed of a thermoplastic resin to one surface or both surfaces of a polarizer has been common.
With widespread use of flat-panel televisions and mobile devices, a smaller thickness of a polarizing plate has increasingly been demanded. A method using a substrate film which is also herein called a “coating method” has been known as a method for producing a polarizing plate including a small-thickness polarizer [for example, Japanese Patent Laying-Open No. 2011-128486 (PTD 1)].
The coating method normally includes the steps of forming a resin layer on a substrate film by application, obtaining a polarizing laminated film by processing the resin layer to a polarizing layer through stretching and dyeing, bonding a protective film to the polarizing layer of the polarizing laminated film, and peeling off the substrate film after the protective film is bonded. With this method, decrease in thickness of the polarizing layer and the polarizing plate can readily be achieved. In addition, since the small-thickness polarizing layer and the resin layer which is a precursor thereof are always supported by the substrate film or the protective film and the polarizing layer and the resin layer are not handled alone, handleability of a film during the process is also excellent.